Demand Duo H-Series with SENSEI CX Installation Instructions 2
If the information in these instructions is not followed exactly, a fire or
explosion may result causing property damage, personal injury, or death.
• Do not store or use gasoline or other flammable vapors and liquids in the vicinity of this or any other
appliance.
• WHAT TO DO IF YOU SMELL GAS
− Do not try to light any appliance.
− Do not touch any electrical switch; do not use any phone in your building.
− Immediately call your gas supplier from a neighbor’s phone. Follow the gas supplier’s
instructions.
− If you cannot reach your gas supplier, call the fire department.
• Installation and service must be performed by a trained and qualified professional, service agency
or the gas supplier.
WARNING WARNING
CHS 199 100 H V A i N/P
Commercial Hybrid System
(Demand Duo)
Max KBTU Input
(398, 320, 199, 160, 130)
Tank Capacity
(119, 80)
Series
(H=High Efficiency, R=Regular Efficiency)
Special Designation
(V=Vertical, A=ASME Tank)
Indoor (all models)
Gas Type (NG or LPG)
Example: CHS398100HVCXAIN
Copyright 2024 Rinnai America Corporation. Rinnai® is a registered trademark of Rinnai Corporation
used under license by Rinnai America Corporation. Rinnai America Corporation continually updates
materials, and as such, content is subject to change without notice.
Demand Duo H-Series with SENSEI CX Installation Instructions 3
READ AND SAVE THESE INSTRUCTIONS
1. Welcome ........................................................................................................................... 4
1.1 To The Installer ........................................................................................................... 4
1.2 To The Owner ............................................................................................................. 4
2. Safety ................................................................................................................................ 5
2.1 Safety Symbols ........................................................................................................... 5
2.2 Safety Precautions ...................................................................................................... 5
3. About ................................................................................................................................. 7
3.1 Components ................................................................................................................ 7
3.2 Specifications .............................................................................................................. 8
3.3 Dimensions ................................................................................................................. 11
4. Installation Preparation ..................................................................................................... 13
4.1 Guidelines ................................................................................................................... 13
4.2 Typical Installations .................................................................................................... 14
4.3 Confirm Shipping Contents ......................................................................................... 15
4.4 What You Will Need .................................................................................................... 16
4.5 Choose an Installation Location ................................................................................. 16
5. Installation Instructions ...................................................................................................... 18
Step 1: Transport .............................................................................................................. 18
Step 2: Secure for Earthquake ......................................................................................... 18
Step 3: Position Tank and Connect Water ....................................................................... 19
Step 4: Install Rack Frame Legs ...................................................................................... 20
Step 5: Position Rack........................................................................................................ 21
Step 6: Install Water Flex Lines ........................................................................................ 22
Step 7: Secure Rack ......................................................................................................... 23
Step 8: Install Vent System ............................................................................................... 24
Step 9: Install Relief Valve Lines ...................................................................................... 25
Step 10: Fill System with Water ........................................................................................ 27
Step 11: Connect Condensate Drain Line ........................................................................ 28
Step 12: Connect Gas Supply .......................................................................................... 29
Step 13: Connect Power Supply ....................................................................................... 30
6. Post Installation Checklist ................................................................................................. 32
7. Maintenance ...................................................................................................................... 33
8. Appendices ........................................................................................................................ 34
8.1 Piping Diagram for Basic Installations ........................................................................ 34
8.2 Controller Diagnostics ................................................................................................. 35
8.3 Replacement Parts ..................................................................................................... 36
9. Warranty ............................................................................................................................ 39
Demand Duo H-Series with SENSEI CX Installation Instructions 4
Thank you for purchasing Rinnai’s Demand
Duo Commercial Hybrid Water Heating
System.
This manual provides information on the
installation, operation, and maintenance of the
system. Read this manual completely before
installing or operating the system.
This manual is a supplement to the Installation
and Operation Manual for Commercial CX199iN
AND CX160iN Condensing Tankless Water
Heaters; refer to the CX199iN AND CX160iN
manual for complete water heater information.
For Your Records
Dealer Name:
Dealer Phone #:
Purchase Date:
Demand Duo Serial #:
Rack Serial #:
• A trained and qualified professional must
install the system, inspect it, and leak test it
before use. The warranty will be voided due
to any improper installation.
• The trained and qualified professional should
have skills such as:
− Gas line sizing
− Connecting gas lines, water lines, valves,
and electricity
− Knowledge of applicable national, state,
and local codes
− Installing venting through a wall or roof
− Training in installation of tankless water
heaters. Training on Rinnai Tankless
Water Heaters is accessible at
rinnaipro.myabsorb.com
• Read all instructions in this manual before
installing the system. The system must be
installed according to the exact instructions in
this manual.
• Proper installation is the responsibility of the
installer.
• When installation is complete, leave this
manual with the system or give the manual
directly to the consumer.
• You must read the entire manual to
properly operate the water heater and to
have regular maintenance performed.
• Keep this manual for future reference.
• As when using any appliance generating
heat, there are certain safety precautions
you should follow. See the Safety
Precautions section for detailed safety
precautions.
• Be sure your water heater is installed by a
licensed installer.
• If installing in the state of Massachusetts,
you must read the Massachusetts State
Gas Regulations section in the tankless
water heater installation and operation
manual (supplied with tankless water
heater).
Demand Duo 2
Serial # and Tank
Serial # located on
the tank on the left
of the tankless
water heater.
Demand Duo
Serial # and Rack
Serial # located on
side of rack frame
leg.
Demand Duo H-Series with SENSEI CX Installation Instructions 5
This manual contains the following important
safety symbols. Always read and obey all safety
messages.
This is the safety alert symbol. This
symbol alerts you to potential hazards
that can kill or hurt you and others.
Indicates an imminently
hazardous situation
which, if not avoided, will result in personal injury
or death.
Indicates a potentially
hazardous situation
which, if not avoided, could result in minor or
moderate injury. It may also be used to alert
against unsafe practices.
DANGER
CAUTION
Indicates a potentially
hazardous situation
which, if not avoided, could result in personal
injury or death.
WARNING
WARNING
• Before operating, smell all around the
appliance area for gas. Be sure to smell next
to the floor because some gas is heavier than
air and will settle on the floor.
• Keep the area around the appliance clear and
free from combustible materials, gasoline, and
other flammable vapors and liquids.
• Combustible construction refers to adjacent
walls and ceiling and should not be confused
with combustible or flammable products and
materials. Combustible and/or flammable
products and materials should never be stored
in the vicinity of this or any gas appliance.
• Always check the water temperature before
entering a shower or bath.
• To protect yourself from harm, before
performing maintenance:
− Turn off the electrical power supply by
unplugging the power cord or by turning off
the electricity at the circuit breaker.
(The “On/Off” button on the temperature
controller does not control the electrical
power.)
− Turn off the gas at the gas valve, usually
located immediately before the water
heater.
− Turn off the incoming water supply. This
can be done at the isolation valve
immediately before the water heater or by
turning off the water supply to the building.
• Use only your hand to push in or turn the gas
control knob. Never use tools. If the knob will
not push in or turn by hand, do not try to
repair it; call a licensed professional. Force or
attempted repair may result in a fire or
explosion.
• Do not use this appliance if any part has been
under water. Immediately call a
licensed professional to inspect the
appliance and to replace any part of the
control system and any gas control which has
been under water.
• Do not use substitute materials. Use only
parts certified for the appliance.
• Should overheating occur or the gas supply
fail to shut off, turn off the manual gas control
valve to the appliance.
• Do not use an extension cord or an adapter
plug with this appliance.
• Any alteration to the appliance or its controls
can be dangerous and will void the warranty.
• If a water heater is installed in a closed water
supply system, such as one having a
backflow preventer in the cold water supply
line, means shall be provided to control
thermal expansion. Contact the water
supplier or local plumbing inspector on how to
control thermal expansion.
• Keep the air intake location free of chemicals
such as chlorine or bleach that produce
fumes. These fumes can damage
components and reduce the life of your
appliance.
• Make sure the water heater and its water lines
are protected from freezing. Damage due to
freezing is not covered by the
warranty.
Topics in this section
• Safety Symbols
• Safety Precautions
Demand Duo H-Series with SENSEI CX Installation Instructions 6
• Only trained and qualified professionals are
permitted to adjust parameter settings.
• Proper venting is required for the safe
operation of this appliance.
• Flammable liquids such as cleaning solvents,
aerosols, paint thinners, adhesives, gasoline
and propane must be handled and stored with
extreme care. These flammable liquids emit
flammable vapors and when exposed to an
ignition source can result in a fire hazard or
explosion. Flammable liquids should not be
used or stored in the vicinity of this or any
other gas appliance.
• DO NOT operate the water heater without the
front panel installed. The front panel should
only be removed for service/maintenance or
replacing internal components.
• BURN HAZARD. Hot exhaust and vent may
cause serious burns. Keep away from the
water heater. Keep small children and animals
away from the water heater.
• Hot water outlet pipes leaving the water heater
can be hot to touch.
• Do not store or use gasoline or other
flammable vapors and liquids in the vicinity of
this or any other appliance.
• Install the vent system per local and national
codes.
• Do not install this water heater above 10,200 ft
(3,109 m).
• Do not obstruct combustion air to the water
heater.
• Failure to properly vent this appliance can
result in death, personal injury and/or property
damage.
• Rinnai recommends that every home have a
carbon monoxide (CO) alarm in the hallway
near bedrooms in each sleeping area. Check
batteries monthly and replace them annually.
DO NOT adjust the
internal gas valve.
The design is such
that adjustment is not required. Warranty will
be voided if the internal gas valve is adjusted.
WARNING
FLAMMABLE
Flammable Vapors
WARNING
FOR YOUR SAFETY
Do not store or use gasoline or other
flammable vapors and liquids in the vicinity of this
or any other appliance.
Hot water can be
dangerous, especially
for infants or children,
the elderly, or infirm.
There is hot water scald
potential if the thermostat
is set too high.
Water temperatures over
125ºF (51ºC) can cause
severe burns or scalding
resulting in death.
Hot water can cause first degree burns with
exposure for as little as:
• 3 seconds at 140ºF (60ºC)
• 20 seconds at 130ºF (54ºC)
• 8 minutes at 120ºF (48ºC)
Test the temperature of the water before placing
a child in the bath or shower.
Do not leave a child or an infirm person in the
bath unsupervised.
DANGER
Demand Duo H-Series with SENSEI CX Installation Instructions 7
• Components
• Specifications
• Dimensions
Topics in this section
Hot Water Outlet
Connection
2-Unit Tankless
Rack System
Gas Line
Cold Water Inlet
Connection
Recovery
Pumps and
Isolation Valves
119-Gallon
Storage Tank
Securing
Bracket
Anode Rod Locations
(left and right side)
Note:
same for both units
Temperature and
Pressure (T&P)
Relief Valve
Vertical Models
Horizontal Models
Electrical Assembly
Drain Valve
Tank Thermistors
Demand Duo H-Series with SENSEI CX Installation Instructions 8
Model Number CHS398100HCX CHS398100HCXA***
Dimensions (Assembled) in. (mm) w x h x d: 38.81 x 71.10 x 45.32 (985.8 x 1,806.8 x 1,151)
Weight
Rack (with 2 Tankless Water Heaters): 220 lbs (100 kg);
Tank: 310 lbs (141 kg) Complete System: 530 lbs (240 kg)
Installation Type Internal (Indoor) Commercial Applications
Category and Ignition System Category IV, Direct Electronic Ignition
Gas Consumption Btu/h (kW/h) Minimum: 30,000 (9) Maximum: 398,000 (116.6)
Water Supply Pressure 150 PSI (Maximum)
Temperature Setting 98°F (37°C) to 185°F (85°C)
Tank Volume 119 Gallons (450 Liters)
First Hour Delivery Rating* 543 Gallons (2,055 Liters)
Sound Level (Single unit) 49 dB
Electrical Data
(CX199iN Tankless Water
Heater)
Normal: 279 W, Standby: 44 W, Freeze Protection: 148 W,
Max Current: 5.5 A
Fuse: Tankless Water Heater Engine: 10 Amps
Gas Supply Pressure** Natural: 3.5 - 10.5 in. w.c. Propane: 8.0 - 13.5 in. w.c.
By-Pass Flow Control Electronic
Connections
Gas Supply Inlet: 1-1/2 in. MNPT Hot Water Outlet: 1-1/2 in. MNPT
Cold Water Inlet: 1-1/2 in. MNPT
Electric Connections
Appliance: AC 120 Volts, 60Hz.
Integrated Temperature Controller: DC 12 Volts (Digital)
Water Flow Control Water Flow Sensor, Electronic Water Control and Bypass Control
Water Temperature Control Simulation Feed Forward and Feedback
Recovery 459 GPH @ 100° ∆T
High Altitude Approved Up to 10,200 Ft (3,109 M)
Complies with South Coast Air
Quality Management District 14
ng/J or 20 ppm NOx Emission
Levels (CX199i)
Yes
Ultra Low NOx Yes
Certifications
AHRI, ANSI Z21.10.3, CSA 4.3 and ENERGY STAR® Certified
(CX199iN)***
Controller (One per Tankless
Water Heater)
MCC-601
Recovery Pump Qty 2 Grundfos UPML 25-104
Venting Material Polypropylene, PVC, CPVC
Venting Options
Concentric Polypropylene, Twin Pipe, or Common Vent
Polypropylene/PVC/CPVC. Vent lengths up to 150 ft.
Wi-Fi Ready Yes
*First Hour Delivery Rating is a theoretical calculation based on 70% usable tank capacity.
Tank Capacity x .70 + (recovery) = First Hour Delivery Rating
** Maximum gas supply pressure must not exceed the value specified by the manufacturer.
***ENERGY STAR® certification for the CX199iN tankless engine is listed on the residential ENERGY
STAR® website.
Demand Duo H-Series with SENSEI CX Installation Instructions 9
*First Hour Delivery Rating is a theoretical calculation based on 70% usable tank capacity.
Tank Capacity x .70 + (recovery) = First Hour Delivery Rating
**Maximum gas supply pressure must not exceed the value specified by the manufacturer.
***Model includes an AMSE rated tank.
****ENERGY STAR® certification for the CX199iN and CX160iN tankless engines is listed on the
residential ENERGY STAR® website.
Model Number CHS398100HVCX CHS398100HVCXA*** CHS320100HVCXIN
Dimensions
(Assembled) in. (mm)
w x h x d: 33.7 x 81.09 x 40.1 (856 x 2,060 x 1,021.1)
Weight
Tank: 310 lbs (141 kg) Complete System: 530 lbs (240 kg)
Installation Type Internal (Indoor) Commercial Applications
Category and Ignition
System
Category IV, Direct Electronic Ignition
Gas Consumption Btu/h
(kW/h)
Minimum: 30,000 (9)
Maximum: 398,000 (116.6)
Minimum: 30,000 (9)
Maximum: 320,000 (93.7)
Water Supply Pressure
150 PSI (Maximum)
Temperature Setting
98°F (37°C) to 185°F (85°C)
Tank Volume
119 Gallons (450 Liters)
First Hour Delivery
Rating*
551 Gallons (2,085 Liters) 460 Gallons (1,741 Liters)
Sound Level
(Single unit)
49 dB 48 dB
Electrical Data
(Tankless Water Heater)
Normal: 265 W,
Standby: 44 W,
Freeze Protection: 148 W,
Max Current: 5.5 A
Normal: 233 W,
Standby: 44 W,
Freeze Protection: 148 W,
Max Current: 5.5 A
Fuse: Tankless Water Heater Engine: 10 Amps, Controller: 10 Amps
Gas Supply Pressure**
Natural: 3.5 - 10.5 in. w.c. Propane: 8.0 - 13.5 in. w.c.
By-Pass Flow Control
Electronic
Connections
Gas Supply Inlet: 1-1/2 in. MNPT Hot Water Outlet: 1-1/2 in. MNPT
Cold Water Inlet: 1-1/2 in. MNPT
Electric Connections
Appliance: AC 120 Volts, 60Hz.
Integrated Temperature Controller: DC 12 Volts (Digital)
Water Flow Control
Water Flow Sensor, Electronic Water Control and Bypass Control
Water Temperature
Control
Simulation Feed Forward and Feedback
Recovery
459 GPH @ 100° ∆T 376 GPH @100° ∆T
High Altitude Approved Up to 10,200 Ft (3,109 M)
Ultra Low NOx Yes
Certifications
AHRI, ANSI Z21.10.3, CSA
4.3 and ENERGY STAR®
Certified (CX160iN)****
AHRI, ANSI Z21.10.3, CSA 4.3 and ENERGY
STAR® Certified (CX199iN)****
Controller MCC-601
Recovery Pump Grundfos UPS 26-150 (S)F; 3 Speed
Venting Material
Polypropylene, PVC, CPVC
Venting Options
Concentric Polypropylene, Twin Pipe, or Common Vent Polypropylene/PVC/
CPVC. Vent lengths up to 150 ft.
Wi-Fi Ready
Yes
Demand Duo H-Series with SENSEI CX Installation Instructions 10
U.S. Gallons / Hour Liters / Hour at Temperature Rise Indicated
Tank
Capacity
°F 30 40 50 60 70 80 90 100 110 120 130 140
°C 17 22 28 33 39 45 50 56 61 67 72 78
119 Gal. GPH 1,528 1,147 917 764 655 573 510 459 417 382 353 328
450 Liters LPH 5,784 4,342 3,471 2,892 2,479 2,169 1,931 1,738 1,579 1,446 1,336 1,242
Recovery Capabilities for CHS398100 models
U.S. Gallons / Hour Liters / Hour at Temperature Rise Indicated
Tank
Capacity
°F 30 40 50 60 70 80 90 100 110 120 130 140
°C 17 22 28 33 39 45 50 56 61 67 72 78
119 Gal. GPH 1,254 941 752 627 537 470 418 376 342 314 289 269
450 Liters LPH 4,747 3,561 2,848 2,374 2,035 1,780 1,582 1,424 1,295 1,187 1,096 1,017
Recovery Capabilities for CHS320100HV
Demand Duo H-Series with SENSEI CX Installation Instructions 11
Measurements below
are shown in inches
(millimeters).
Models
CHS398100HCX
CHS398100HCXA
LEFT
*Temperature and Pressure Relief Valve
RIGHT
58.30 in.*
(1481 mm)
43.72 in. (1110 mm) GAS
45.20 in. (1,148 mm)
TOP
Ø 28.16 in.
(715 mm)
43.80 in. (1112 mm)
39.93 in. (1014 mm)
Gas
Vent
45.32 in. (1151 mm)
38.81 in. (986 mm)
20.50 in.
(521 mm)
5.91 in. (150 mm)
Typical
* Temperature and Pressure Relief Valve
FRONT
4.14 in.
(105 mm)
Cold
69.40 in. (1762 mm) Tank Height
34.02 in. (864 mm)
71.1 in. (1806 mm) Hot
Gas
65.04 in. (1652 mm) PVC/PP
Demand Duo H-Series with SENSEI CX Installation Instructions 12
Models
CHS398100HVCX
CHS398100HVCXA
CHS320100HVCX
Measurements below
are shown in inches
(millimeters).
RIGHT
69.40 (1762)
71.1 (1806) Hot
FRONT
51.12 (1298) Gas
58.30 (1481) T&P
67.48 (1714) Electric
81.09 (2060)
40.39 (1026)
4.14 (105)
1-1/2 in. MNPT
Cold
TOP
Ø 28.16 (715)
28.76 (730)
Gas
34.67 (880) Vent
40.06 (1,017)
18.12 (460)
T&P
Demand Duo H-Series with SENSEI CX Installation Instructions 13
THIS SECTION IS INTENDED FOR THE
INSTALLER
Installer qualifications: A trained and qualified
professional must install the appliance, inspect it,
and leak test the Demand Duo
before use.
The warranty will be voided due to any improper
installation. The trained and qualified professional
should have skills such as: Gas sizing;
Connecting gas lines, water lines, valves, and
electricity; Knowledge of applicable national,
state, and local codes; Installing venting through
a wall or roof; and training in installation of
tankless water heaters. Training for Rinnai
Tankless Water Heaters is accessible online at
rinnaipro.myabsorb.com.
• This water heater is suitable for combination
water heating and space heating and not
suitable for space heating applications only.
• The installation must conform with local
codes or, in the absence of local codes, with
the National Fuel Gas Code, ANSI Z223.1/
NFPA 54, or the Natural Gas and Propane
Installation Code, CSA B149.1.
• The appliance, when installed, must be
electrically grounded in accordance with local
codes or, in the absence of local codes, with
the National Electrical Code, ANSI/NFPA 70,
or the Canadian Electrical Code, CSA C22.1.
• You must follow the installation instructions
and those in the venting section for adequate
combustion air and exhaust.
When installing the Demand Duo
, follow
these guidelines:
• The appliance and its main gas valve must be
disconnected from the gas supply piping
system during any pressure testing of that
system at test pressures in excess of 1/2 psi
(3.5 kPa) (13.84 in W.C.). For system testing
at pressures less than or equal to 1/2 psi
(3.5 kPa) (13.84 in W.C.) the appliance must
be isolated from the gas supply piping by
closing its individual manual shutoff valve.
• If a water heater is installed in a closed water
supply system, such as one having a
backflow preventer in the cold water supply
line, means shall be provided to control
thermal expansion. Contact the water supplier
or local plumbing inspector on how to control
thermal expansion.
• Should overheating occur or the gas supply
fail to shut off, turn off the manual gas control
valve to the appliance.
• Combustion air must be free of chemicals,
such as chlorine or bleach, that produce
fumes. These fumes can damage
components and reduce the life of your
appliance.
• DO NOT install the Demand Duo
outdoors.
• DO NOT install the Demand Duo in an
area where water leakage of the unit or
connections will result in damage to the area
adjacent to the system or to lower floors of
the structure. When such locations cannot be
avoided, it is recommended that a suitable
drain pan, adequately drained, be installed
under the water heaters. The pan must not
restrict combustion air flow.
• DO NOT install the Demand Duo
in an
area with negative air pressure, where the
pressure inside is lower than the pressure
outside.
• DO NOT obstruct the flow of combustion and
ventilation air.
• DO NOT use the Demand Duo
in an
application such as a pool or spa heater that
uses chemically treated water. The Demand
Duo is suitable for filling large or whirlpool
spa tubs with potable water.
• DO NOT use substitute parts that are not
authorized for this system.
• DO NOT connect power to the Demand
Duo
prior to completing installation and
the system has been filled with water.
Topics in this section
• Guidelines
• Typical Installations
• Confirm Shipping Contents
• What You Will Need
• Choose an Installation Location
Demand Duo H-Series with SENSEI CX Installation Instructions 14
#
Item
Field
Supplied
❶
Hot Water Outlet
✓
❷
Hot Water Outlet
Shut-Off Valve
✓
❸
Cold and Hot
Unions
✓
❹
Temperature-
Pressure
Relief Valve
Discharge Pipe (do
not cap, plug or
reduce)
✓
❺
Pressure Relief
Valve
Discharge Pipes
(do not cap, plug,
or reduce)
✓
❻
Controller
✓
❼
Condensate
Discharge Pipe
(must include an air
gap)
❽
Gas Control Valve
✓
❾
Gas Union
✓
❿
Cold Water Supply
Shut-Off Valve
✓
⓫
Cold Water Supply
✓
⓬
Thermal Expansion
Tank
✓
⓭
Non-Tempered
Supply Line
✓
⓮
Thermostatic
Mixing Valve
✓
⓯
Non-Tempered
Return Line
✓
Installation with Mixing Valve
Cold water line and expansion tank
locations are altered for illustrative
purposes.
IMPORTANT
⓭
⓮
⓯
❶
❷
❸
❻
❸
❹
❼
❽
❿
⓫
⓬
❺
❾
Demand Duo H-Series with SENSEI CX Installation Instructions 15
To avoid danger of
suffocation, keep
plastic bags away
from babies, small children and pets. Do not
use these bags in cribs, beds, carriages, or
playpens. The bags are not a toy.
WARNING
• 119-Gallon Storage Tank
• Electric Assembly
• Upper and Lower Tank Thermistors
The Demand Duo Commercial Hybrid Water Heating System is packaged and shipped in two
separate shipping boxes for horizontal units. Carefully unpack the shipping boxes and verify the
following contents are included.
If any items are damaged or missing, contact your local dealer/distributor or call Rinnai Customer Care
at 1-800-621-9419. Do not attempt to use any item that appears damaged.
• Rack System with two (2) pre-installed
Rinnai Tankless Water Heaters
• Frame Legs (Qty 2)
• Recovery Pumps (Qty 2)
• Water Flex Lines (Qty 2)
• 18 in. (457 mm)
• 36 in. (914 mm)
• 5/16 in.-18 Bolts (Qty 4) (not shown in image)
• Securing Bracket
• Documentation:
• Demand Duo Commercial Hybrid
Water Heating System Installation and
Operation Manual (this manual)
• Tankless Water Heater Installation and
Operation Manual
Shipping Box 1
Shipping Box 2
Assembled View
Securing Bracket
Water Flex Line
36 in. (914 mm)
Water Flex Line
18 in (457mm)
2-Unit Tankless
Rack System
Frame Legs (Qty 2)
Recovery Pumps
Upper Thermistor
Electric Assembly
Assembled View
119 Gallon
Storage Tank
Lower Thermistor
Demand Duo H-Series with SENSEI CX Installation Instructions 16
Gather the recommended tools and materials
before starting installation.
Contaminant Maximum Level
Total Hardness Up to 200 mg/L
Aluminum * Up to 0.2 mg/L
Chlorides * Up to 250 mg/L
Copper * Up to 1.0 mg/L
Dissolved Carbon Dioxide
(CO2)
Up to 15.0 mg/L
Iron * Up to 0.3 mg/L
Manganese * Up to 0.05 mg/L
pH * 6.5 to 8.5
TDS (Total Dissolved Solids) * Up to 500 mg/L
Zinc * Up to 5 mg/L
When selecting an installation location, you must
ensure that clearances will be met and that the
vent length will be within required limits. Consider
the installation environment, water quality, and
need for freeze protection. Requirements for the
gas line, water lines, electrical connection, and
condensate disposal can be found in their
respective sections in this manual.
For vent termination clearances, refer to the
Tankless Water Heater Installation and Operation
Manual supplied with the Demand Duo
system.
* Source: Part 143 National Secondary Drinking
Water Regulations
This section provides information on the
importance of water quality to the Rinnai
Tankless Water Heater. The information is
intended to serve as general guidelines only and
is not a complete list of water quality guidelines.
Consideration of care for your water heater
should include evaluation of water quality.
The water must be potable, free of corrosive
chemicals, sand, dirt, or other contaminants. It is
up to the installer to ensure the water does not
contain corrosive chemicals or elements that can
affect or damage the Rinnai Tankless Water
Heater. Water that contains chemicals exceeding
the levels below can damage the Rinnai
Tankless Water Heater. Replacement of
components due to water quality damage is not
covered by the warranty.
• Pipe wrenches (x2)
• Phillips Head screwdriver
• Adjustable pliers
• Wire cutters
• Hoisting straps (able to support
approximately 220 lb/100 kg)
• Gloves
• Safety glasses
• Level
• Soap or gas leak detector solution
• Approved venting
• Teflon tape (recommended) or pipe
compound
• Pipe insulation
• Hammer drill with concrete bits
• Saw
• Threading machine with heads and oiler
• Core drill with diamond head
• Torch set
• Copper tubing cutter
• Steel pipe cutter
• Heat tape
• Electrical wire
• Concrete wall anchors
• Optional pipe cover
• PVC glue/cement and primer
• 2 conductor 22 AWG wire for controller
• Single gang electrical box
• Wire nuts
• Unions and drain valves
• Drain pan
• Earthquake strap
Demand Duo H-Series with SENSEI CX Installation Instructions 17
Air surrounding the water heater, venting, and
vent termination(s) is used for combustion and
must be free of any compounds that cause
corrosion of internal components. These include
corrosive compounds that are found in aerosol
sprays, detergents, bleaches, cleaning solvents,
oil based paints/varnishes, and refrigerants. The
air in beauty shops, dry cleaning stores, photo
processing labs, and storage areas for pool
supplies often contains these compounds.
Therefore, it is recommended to install as a direct
vent (use outside air for combustion). In
applications utilizing room air where there are
high levels of particulates, Rinnai offers a room
air screen. The water heater, venting, and vent
termination(s) should not be installed in any areas
where the air may contain these corrosive
compounds.
If you install the Demand Duo
in an area that
is known to have hard water or that causes scale
build-up, the water must be treated and may
require a more frequent flushing schedule.
This water heater includes a service indicator
(Service Soon, SS). When selected in the
parameter settings, an SS code will display on the
controller indicating that it is time to flush and
service the water heater. Scale build-up is
caused by hard water and can be accelerated if
the water heater is set at a temperature above
120°F.
Rinnai offers Southeastern Filtration’s
“ScaleCutter Water Conditioning System” that
offers superior lime scale prevention and
corrosion control by feeding a blend of control
compounds into the cold water supply.
Location Clearance
Top of tank
• 12 in. (305 mm)
• 0 in. from vent components
• Clearance for servicing the
anode rods is 54 in. (1.4 m)
from top of water heater
Bottom
(Ground)
0 in.
Back of tank 0 in.
Front of
tankless water
heaters
0 in.
Clearance for servicing is 24
in. (610 mm)
Sides (Left and
Right) of
tankless water
heaters
2 in. (51 mm)
12 in.
(305 mm)
2 in.
(51 mm)
24 in.
(610 mm)
Demand Duo H-Series with SENSEI CX Installation Instructions 18
1. Choose the right hand truck to support the
weight and size of the water heater. Refer to
the Specifications section in this manual for
specific weights and dimensions.
2. Use proper lifting techniques to load the tank
onto the hand truck:
• Position the tank onto the hand truck so
the weight is evenly balanced and the
tank is touching the rails of the hand
truck.
• Secure the water heater to the hand
truck:
Position STRAP A around the top of
the tank as illustrated below.
Position STRAP B around the base of
the tank below the pump assembly.
Products installed in the state of California must
be braced, anchored, or otherwise secured to
avoid motion or falling during an earthquake.
Contact the California Office of the State
Architect located at 1102 Q Street, Suite 5100,
Sacramento, CA 95811 for instructions.
NOTICE
STRAP
STRAP
Position straps around the tank per the
requirements of California Office of the State
Architect. DO NOT POSITION THE STRAPS
OVER PUMP, PIPE, FITTINGS OR WIRE.
IMPORTANT
Topics in this section
Step 1: Transport
Step 2: Secure for Earthquake
Step 3: Position Tank and Connect Water
Step 4: Install Rack Frame Legs
Step 5: Position Rack
Step 6: Install Water Flex Lines
Step 7: Secure Rack
Step 8: Install Vent System
Step 9: Install Relief Valve Lines
Step 10: Fill System with Water
Step 11: Connect Condensate Drain Line
Step 12: Connect Gas Supply
Step 13: Connect Power Supply
Strap B
Strap A
Demand Duo H-Series with SENSEI CX Installation Instructions 19
When positioning the tank and connecting water, follow these guidelines:
• Water connections to the Demand Duo must follow all state and local plumbing codes.
• When assembling the hot and cold water piping, use a high quality food grade pipe joint compound
and ensure all fittings are tight.
• DO NOT apply an open flame to the inlet and outlet fittings, as heat will damage or destroy the
plastic lined fittings. This will result in premature failure of the fittings, which is not covered by the
warranty.
• For standard installations, refer to the Piping Diagram for Basic Installations in the Appendix.
To position the tank and connect water:
1. Position the tank in the desired location.
2. Connect piping to the cold water inlet connection (1.5 in./38 mm MNPT). See A in image below.
• Keep the pipe as close as possible to one side of the tank; this allows the rack frame to position
closer to the tank and allow for easier flex line connection (see B).
• Maximum pipe length from the cold water inlet connection to the rack frame leg is 17.77 in.
(451 mm) (see C).
3. Connect piping to the hot water outlet connection (1.5 in./38 mm MNPT) (see D).
4. Install a shut-off valve on the cold and hot water lines (see E).
5. Rinnai recommends to install unions on the cold and hot water lines so that the water heater can
easily disconnect if servicing is required (see F).
Keep pipe
close to
tank
B
F
F
E
E
A
F
E
A
E
D
17.77 in.
(451 mm)
MAXIMUM
C
Demand Duo H-Series with SENSEI CX Installation Instructions 20
1. Lay the rack assembly down on the
shipping pallet.
2. Position the frame legs (supplied)
on each rack leg so that the
threaded inserts are centered over
the open slots.
3. Use the supplied 4
bolts (5/16 in. - 18)
to fasten the frame
legs to the rack
legs.
Frame leg
Threaded
inserts
To install the rack frame legs:
The pallet may need to be
elevated to complete
assembly.
NOTE
Demand Duo H-Series with SENSEI CX Installation Instructions 21
1. Loop hoisting straps (field-supplied) around the rack top frame. Straps should support approximately
220 lb (100 kg).
2. Position the rack in front of the tank, and then gently push the rack back as close to the tank as
possible so that the flex lines can connect the two assemblies.
Loop hoisting straps around rack top
frame.
To position the rack:
Place rack in front of tank
17.77 in. (451 mm)
Push rack back close to tank
Demand Duo H-Series with SENSEI CX Installation Instructions 22
1. Connect the 18 in. (457 mm) flex line from the cold water manifold to the threaded connection on the
tank. Tighten to 25 ft-lb torque.
Ensure the gasket is in the flex line.
2. Connect the 36 in. (914 mm) flex line from the hot water manifold to the threaded connection at the
top of the tank. Tighten to 25 ft-lb torque.
To install flex lines:
36 in. (914 mm)
flex line
Hot water manifold
Threaded connection
at top of tank
18 in. (457 mm) flex line
Threaded connection
on tank
Cold water manifold
Demand Duo H-Series with SENSEI CX Installation Instructions 23
1. The rack system must be
anchored and secured in
accordance with national and/or
local codes having jurisdiction.
Base holes to secure the rack
are 0.5 in. (13 mm) in diameter.
Reference local codes
regarding minimum concrete
thickness and use appropriate
expansion anchors that are
capable of supporting the rack
system weight of approximately
220 lb (100 kg). Reference and
follow the anchor
manufacturer’s use and
installation requirements.
Bottom View
2. Place the securing bracket on top
of the tank and over the frame of
the rack.
3. Using (4) self-drilling screws,
attach the securing bracket to
the top of the tank.
To secure the rack:
Demand Duo H-Series with SENSEI CX Installation Instructions 24
Refer to the Tankless Water Heater Installation and Operation Manual (supplied with each Tankless
Water Heater in the Demand Duo system) for complete venting information and instructions. Topics
in this manual include: Venting Guidelines; Venting Installation Sequence and Instructions; Venting
Options; Maximum Vent Lengths; and Termination Considerations.
To secure the rack:
For vertical model installations, please refer to the recommended venting configuration shown in the
image below.
3 in. PVC
2 in. PVC
2 in. PVC
Demand Duo H-Series with SENSEI CX Installation Instructions 25
A Pressure Relief Valve (PRV) is pre-installed on each tankless water heater in the Demand Duo
system. A combination Temperature and Pressure (T&P) Relief Valve is pre-installed on the tank. Install
a drain pipe from each PRV and T&P Valve into a floor drain as shown in the diagram below. Refer to
the guidelines on the next page.
To secure the rack:
PRV location on Tankless
Water Heater
Pipe to open drain
T&P
Relief Valve
on tank
Demand Duo H-Series with SENSEI CX Installation Instructions 26
• An approved PRV (pre-installed on each
tankless water heater in the Demand Duo
system) is required by the American National
Standard (ANSI Z21.10.3) for all water heating
systems and shall be accessible for servicing.
• The PRV must comply with the standard for
Relief Valves and Automatic Gas Shutoff
Devices for Hot Water Supply Systems ANSI
Z21.22 and /or the standard Temperature,
Pressure, Temperature and Pressure Relief
Valves and Vacuum Relief Valves, CAN1-4.4.
• The PRV must be rated up to 150 psi and to at
least the maximum BTU/hr of the appliance.
• The discharge from the PRV should be piped
to the ground or into a drain system per local
codes.
• The PRV must be manually operated once a
year to check for correct operation.
• The PRV should be added to the hot water
outlet line and near the hot water outlet
according to the manufacturer’s instructions.
DO NOT place any other type valve or shut-off
device between the PRV and the water
heater.
• If a PRV discharges periodically, this may be
due to thermal expansion in a closed water
supply system. Contact the water supplier or
local plumbing inspector on how to correct this
situation. Do not plug the PRV.
• For safe operation, the relief valve(s) must not
be removed from its designated point of
installation or plugged.
• An approved T&P Relief Valve is required by
the American National Standard (ANSI
Z21.10.3) for all water heating systems and
shall be accessible for servicing.
• The T&P Relief Valve must comply with the
standard for Relief Valves and Automatic Gas
Shutoff Devices for Hot Water Supply
Systems ANSI Z21.22 and /or the standard
Temperature, Pressure, Temperature and
Pressure Relief Valves and Vacuum Relief
Valves, CAN1-4.4.
• The T&P Relief Valve must be rated up to 150
psi and to at least the maximum BTU/hr of the
appliance.
• The discharge from the T&P Relief Valve
should be piped to the ground or into a drain
system to prevent exposure or possible burn
hazards to humans or other plant or animal
life. Follow local codes. Water discharged
from the relief valve could cause severe burns
instantly, scalds, or death.
• The T&P Relief Valve must be manually
operated once a year to check for correct
operation.
WARNING
• Water discharged from the PRV could cause
severe burns instantly or death from scalds.
• DO NOT plug the PRV and do not install
any reducing fittings or other restrictions in
the relief line. The relief line should allow for
complete drainage of the valve and the line.
• DO NOT place any other type valve or shut-
off device between the PRV and the water
heater.
• DO NOT pipe the T&P Relief Valve, PRV,
and/or condensate drain together into a
common pipe.
WARNING
• DO NOT plug the T&P Relief Valve and do
not install any reducing fittings or other
restrictions in the relief line. The relief line
should allow for complete drainage of the
T&P Relief Valve and the line.
• DO NOT place any other type valve or shut
off device between the T&P Relief Valve and
the water heater.
• DO NOT pipe the T&P Relief Valve, PRV,
and/or condensate drain together into a
common pipe.
Demand Duo H-Series with SENSEI CX Installation Instructions 27
When filling the system with water, follow these guidelines:
• To prevent damage to the water heater, all air must be relieved from the system and a hot
water fixture must be flowing water before the water heater is plugged in and turned on.
DO NOT OPERATE THE WATER HEATER UNLESS IT IS COMPLETELY
FULL OF WATER.
NOTICE
To fill the system with water:
1. Ensure the drain valve located at the bottom of the tank is closed (see A below).
2. Open the nearest hot water fixture.
3. Open the cold water supply valve to the water heater (see B).
4. Keep the hot water fixture open until the tank is filled and constant flow is obtained at the fixture.
5. Close the hot water fixture.
6. Check water heater connections and plumbing system for damage or leaks. Repair if needed.
7. Connect a hose (such as a standard garden hose) to the cold drain valve on one of the tankless
water heaters and open the valve to allow water out; this ensures no air is trapped inside the pump
(see C).
A
B
C
A
B
Demand Duo H-Series with SENSEI CX Installation Instructions 28
Condensate can form in the vent of high
efficiency, direct vent tankless water heaters.
Without proper drainage, condensate will damage
the heat exchanger located inside the tankless
water heater.
When connecting the condensate drain line,
follow these guidelines:
• Use only corrosion-resistant materials for the
condensate drain lines, such as PVC pipe or
plastic hose.
• The condensate drain line should be as short
as possible and have a downward pitch.
• The end of the condensate drain line should
be open to the atmosphere. The end should
not be under water or other substances.
WARNING
EXTERNAL TRAP
NOT PERMITTED
• DO NOT connect the condensate drain line
directly to the rain sewer.
• DO NOT connect the condensate drain line
with an air conditioning evaporator coil drain.
• DO NOT pipe condensate drain,
temperature-pressure relief valve, and/or
pressure relief valve together into a common
pipe.
• Water heaters have an integrated condensate
trap. DO NOT install an external condensate
trap.
To connect the condensate line:
Place the condensate drain line (1/2 in. clear
vinyl tubing) towards the drain.
Keep the drain line open to the atmosphere and
NOT under water or other substances.
• Ensure that the condensate drain, PRV, and
T&P Relief Valve are piped separately to their
own dedicated drain lines.
• If the condensate drain gets blocked, a
diagnostic code will display on the controller.
If this occurs, the condensate drain must be
cleaned.
• The condensate trap will automatically prime
(self-prime) during operation of the unit as
condensate forms. Condensate draining from
the unit indicates that the trap is full and that
there is no blockage in the condensate drain.
It is not necessary to add water to the
condensate trap.
• A condensate neutralizer kit is available from
Rinnai. The kit allows condensate to flow
through neutralizing media that raises the pH
of the condensate to a level that will help
prevent corrosion of the drain and public
sewer system.
CORRECT
Drain line open to
atmosphere
Water
Drain line submerged
in water
NOT CORRECT
Water
Condensate Drain Line
(1/2 in. Clear Vinyl
Tubing)
• All condensate must drain and be disposed
of according to local codes.
Demand Duo H-Series with SENSEI CX Installation Instructions 29
• A licensed professional must install the gas supply.
• Turn off 120V power supply.
• Turn off the gas.
• Gas is flammable. Do not smoke or provide other ignition sources while working with gas.
• Do not turn on the water heater or gas until all fumes are gone.
WARNING
1. Install a manual gas control valve in the gas supply line to the water heater. A union can be used on
the connection above the shut off valve for the future servicing or disconnection of the water heater
(see image below).
2. Check the type of gas and gas supply pressure before connecting the water heater. If the water
heater is not of the gas type that the building is supplied with, DO NOT connect the water heater.
Contact the dealer for the proper water heater to match the gas type.
3. Check the gas supply pressure immediately upstream at a location provided by the gas company.
Supplied gas pressure must be within the limits shown in the Specifications section of this manual
with all gas appliances operating.
4. Before placing the appliance in operation, all joints, including the water heater, must be checked for
gas tightness by means of soap, gas leak detector solution, or an equivalent nonflammable solution,
as applicable. Since some leak test solutions, including soap and water, may cause corrosion or
stress cracking, rinse the piping with water after testing, unless it has been determined that the leak
test solution is non-corrosive.
5. Use approved connectors to connect the water heater to the gas line. Purge the gas line of any debris
before connection to the water heater.
6. Any compound used on the threaded joint of the gas piping must be chemically compatible and
mechanically suitable to be used in liquefied petroleum gas (LPG/Propane) applications.
7. The gas supply line shall be gas tight, sized, and installed to provide a supply of gas sufficient to
meet the maximum demand of the water heater and all other gas-consuming appliances at the
location without loss of pressure. If in doubt about the size of the gas line, refer to the Installation and
Operation Manual for Commercial CX199iN Condensing Tankless Water Heaters.
8. Perform a leak and pressure test prior to operating the water heater. If a leak is detected, do not
operate the water heater until the leak is repaired.
To connect the gas supply:
Union
Gas
Valve
Gas
Valve
Union
Demand Duo H-Series with SENSEI CX Installation Instructions 30
1. An electrical assembly is pre-installed on the
storage tank for single point electrical
connection (Refer to the Specifications
sections in this manual for electrical
requirements.
Connect power to the electrical assembly by
following the steps on the following page.
WARNING
• Do not use an extension cord or adapter plug
with this appliance.
• The water heater must be electrically
grounded in accordance with local codes and
ordinances or, in the absence of local codes,
in accordance with the National Electrical
Code, ANSI/NFPA No.70.
• Indoor water heaters are equipped with a
three-prong (grounding) plug for your
protection against shock hazard and should
be plugged directly into a properly grounded
three-prong receptacle. Do not cut or remove
the grounding terminal from this plug.
When connecting the power supply, follow these
guidelines:
• Do not rely on the gas or water piping to
ground the water heater. Ground locations
are provided inside the water heater.
• Do not exceed the limits of the 15A circuit.
• The water heater requires 120 VAC, 60 Hz
power from a properly grounded circuit.
• Do not connect power to the Demand Duo
2 system prior to completing installation and
filling the system with water.
• The Tankless Water Heater wiring diagram is
located on the inside of the water heater front
cover. The controller wiring diagram is
located on the inside front cover of the
controller.
• When power is supplied, the water heater
maintains pump operation. If the Demand
Duo
system is not in use for an extended
period of time, disconnect power from the
system.
To connect the power supply:
Shut off building supply power prior to
connecting to the electrical assembly. Failure to
do so may result in property damage, bodily
harm, or death.
WARNING
Electrical Assembly
with 20 A, 125 V,
2-Pole, 3-Wire
Grounding
Receptacle
Demand Duo H-Series with SENSEI CX Installation Instructions 31
3. Remove the desired knockout along the
perimeter of the electric box for conduit
installation.
2. Remove the two screws around the
outlet cover. Remove the outlet cover
and prewired outlet.
5. Strip the green, white, and black field
supplied wires 1/2 in. Make sure the
conductors are completely bare.
.
6. Match the wire colors, then grip the wire
firmly and push the conductor into open
port of the push in connector.
1. Locate the electric conduit on the side of
the water heater.
Use only one conductor per port. Verify
conductor is fully inserted to the back of the
connector.
NOTE
4. Install conduit into the knockout opening
and pull the green, white and black wires
into the box.
Demand Duo H-Series with SENSEI CX Installation Instructions 32
Complete the following checklist when installation is complete. You should be able to answer YES to
each question. If you answer NO, installation is not complete. Refer to the applicable section in this
manual and the tankless water heater installation and manual for additional information.
INSTALLATION DETAILS
YES NO
Have you verified the unit, vent and air intakes meet the clearance requirements?
Are parameter settings configured appropriately for the altitude?
Are the tankless water heater front panels installed?
Does the installation conform with local codes or, in the absence of local codes, with the
National Fuel Gas Code, ANSI Z223.1/NFPA 54, or the Natural Gas and Propane Installation
Code, CSA B149.1?
VENTING
YES NO
Are the correct venting products for the installed system being utilized?
Have you followed the venting manufacturer’s installation instructions and the installation
instructions in this document?
Have you verified the water heater is not subject to corrosive compounds in the air?
Have you verified the vent system does not exceed the maximum length for the number of
elbows used?
Did you explain to the customer the importance of not blocking the vent termination or air
intake?
SYSTEM PIPING
YES NO
Have you verified the water supply does not contain chemicals or exceed total hardness that
will damage the heat exchanger?
Did you ensure the hot and cold water lines are not crossed to the unit and are leak free?
Did you place a manual gas control valve in the gas line to the water heater?
Did you ensure that a pressure relief valve is installed with a rating at least the maximum
BTU/hr of the appliance? Refer to the rating plate on the side of the tankless water heater for
BTU input.
Did you clean the inlet water filter by closing the cold and hot water inlet isolation (shut-off)
valves? (Put a bucket under the filter at the bottom of the water heater to catch any water
that is contained inside the unit. Unscrew the water filter. Rinse the filter to remove any
debris. Install the filter and open the isolation valves.)
Have you verified that no toxic chemicals were introduced to the potable water?
Did you drain water from the tankless engines if the water heater is not needed for immediate
use?
GAS SUPPLY
YES NO
Have you performed a gas line and connection leak test?
Is the inlet gas pressure within limits?
Did you verify the water heater is rated for the gas type supplied?
Have you verified the system is functioning correctly by connecting your manometer to the
gas pressure test port on the water heater? Operate all gas appliances in the home or facility
at high fire. The inlet gas pressure at the water heater must not drop below that listed on the
rating plate.
POWER SUPPLY
YES NO
Have you confirmed that the electricity is supplied from a 120 VAC, 60 Hz power source; is in
a properly grounded circuit; and turned on?
Have you verified the temperature controller is functioning properly?
OTHER
YES NO
Have you explained to the customer the operation of the water heater, safety guidelines,
maintenance, and warranty?
Did you leave this manual and the Water Heater Installation and Operation Manual(s) taped
to the water heater? Or you may give both manuals directly to the consumer.
Demand Duo H-Series with SENSEI CX Installation Instructions 33
Drain a pail of water through the drain valve at
least once a year. This will remove excess
sediment from the bottom of the tank. This
sediment, if allowed to accumulate, will reduce
the efficiency and the life of the tank.
To drain the storage tank:
1. Turn off power to the system by unplugging
power to tankless water heaters and digital
controller. (The system will not be fully shut
down by pressing the Power button on the
controller.)
2. Close the cold water supply manual shut-off
valve.
3. Connect one end of a garden hose to the
storage tank drain valve and put the other
end next to a free-flowing drain.
4. Open the drain valve by turning the knob
counter-clockwise.
5. Open a hot water faucet to allow air into the
system.
Storage Tank Anodes
Storage Tank
Anodes
Caps
Drain
Valve
Cold Water
Supply Valve
The storage tank is equipped with two
magnesium anodes designed to extend the life
of the storage tank. Slowly consumed over time,
the anode protects the glass-lined tank from
corrosion. Rinnai strongly recommends to
inspect the anodes every two (2) years. If more
than half of the anodes have been consumed,
they should be replaced. Instructions on how to
change the anodes can be obtained from the
manufacturer.
The longevity of the storage tank can be
reduced when a water softener is introduced to
fight hard water. Sodium salts added by a
softener can make the water extremely
conductive; therefore, the anodes are
consumed at a faster rate. In such conditions,
the anodes should be inspected on a yearly
basis.
In certain conditions, the anodes may react with
the water, producing discolored or smelly water.
The most common complaint is hot water that
smells like rotten eggs. This is the result of the
reaction between the anode and hydrogen
sulphide gas dissolved in the water, which is
common in well systems. This issue can usually
be eliminated or reduced by changing the
magnesium anodes to aluminum anodes and by
chlorinating the storage tank and plumbing
system. If the problem continues, special
filtration equipment may be required. Under no
circumstances are the anodes to be removed
from the water heater on a permanent basis.
Removal of the anodes will lead to
premature failure of the water heater and will
void the warranty.
Demand Duo H-Series with SENSEI CX Installation Instructions 34
When connecting multiple units, balancing valves, equivalent piping, pressure gauges, and temperature
gauges are to be used as necessary to ensure proper flow between units.
Hot Water Supply Line
Condensate
Drain Line
Gas Supply
Building
Circulation Pump
Pipe
Temperature
and Pressure
Relief (T&P)
Valve to Open
Drain
Building Hot Water
Return Line (Optional)
LEGEND
Union
Ball Valve
Check Valve
Circulation Pump
Expansion Tank
Cold Water Supply
Topics in this section
• Piping Diagram for Basic Installations
• Controller Diagnostics
• Replacement Parts
Demand Duo H-Series with SENSEI CX Installation Instructions 35
• Do not use an extension cord or adapter plug with this appliance.
• The water heater must be electrically grounded in accordance with local codes and ordinances or, in
the absence of local codes, in accordance with the National Electrical Code, ANSI/NFPA No. 70.
• The water heater is equipped with a three-prong (grounding) plug for your protection against shock
hazard and should be plugged directly into a properly grounded three-prong receptacle. Do not cut
or remove the grounding terminal from this plug.
WARNING
When connecting the power supply, follow these guidelines:
• Do not rely on the gas or water piping to ground the water heater. Ground locations are provided
inside the water heater.
• The water heater requires 120 VAC, 60 Hz power from a properly grounded circuit.
• Do not connect power to the commercial hybrid system prior to completing installation and the
system has been filled with water.
• The Tankless Water Heater wiring diagram is located on the inside of the water heater front cover.
The controller wiring diagram is located on the inside front cover of the controller.
The ST119CH tank will come with the Upper and Lower Tank Thermistor and the Dual Thermistor
Wiring Adapter. The Thermistor wiring harness will be plugged in to the PCB of each tankless water
heater.
Each tankless water heater will have an upper and lower thermistor wire. Match the lower and upper
thermistor to the proper thermistor in the tank, and plug in.
When power is supplied, the water heaters will maintain pump operation. If
system is not in use for an extended period of time, disconnect power from
the system.
ATTENTION
Demand Duo H-Series with SENSEI CX Installation Instructions 36
❻
❺
❽
❼
❹
❸
❾
❼
❶
❷
ITEM NO. PART # DESCRIPTION
1 CX199iN Rinnai SENSEI CX Tankless Water Heater
2 109001379 TRW02 Frame
3 109000738 Left Frame Base
4 109000739 Right Frame Base
5 107000382 1 in. X 36 in. Water Flex Line
6 107000524 1 in. X 18 in. Water Flex Line
7 109000416 Gas Flex Line
8 109000830 Top Support Bracket
9 109000296 5/16 in.-18 Bolt
Replacement Parts for Horizontal Models
Demand Duo H-Series with SENSEI CX Installation Instructions 37
ITEM NO. PART # DESCRIPTION
1 107000637 119-Gallon Tank
2 105000337 Electrical Assembly
3 107000437
Temperature and Pressure
(T&P) Relief Valve
4 107000438 1 in. Street Elbow NPT
5 107000440 1 in. X 3 in. Dielectric Nipple
6 105002048 Dual Thermistor
7 107000308
1-1/2 in. X 4 in. Dielectric
Nipple
8 107000315
Brass Drain Valve 3/4 in. X
2-3/4 in.
9 107000312 Hand Hole Cleanout Cover
10 109000633
Cleanout Bolts 5/16 in.-18 X
3/4 in.
11 107000311 Tank Cleanout Flange Gasket
12 107000314 Anode Rod, Magnesium
13 105002049
Dual Thermistor Adapter
Harness (this is a wire splitter
that connects the upper and
lower thermistors) (image not
shown)
❾
❿
⓫
❹
❶
⓫
⓬
❸
❻
❽
❺
❼
❷
❼
Demand Duo H-Series with SENSEI CX Installation Instructions 38
Item No. Part Number Description
1 CX199iN/CX160iN
Rinnai SENSEI Tankless
Water Heater
2
107000637
107000672
119 Gallon Tank
119 Gallon ASME Tank (for
ASME models only)
3 107000458
Grundfos UPML 25-104 Pump
4 105000337
Electrical Assembly
5 107000437
Temperature and Pressure
(T&P) Relief Valve
6 107000438
1 in. Street Elbow
7 107000440
1 in. X 3 in. Dielectric Nipple
8 107000671
Isolation Valves
9 105002048
Dual Thermistor
10 105002049
Dual Thermistor Adapter
Harness
11 107000308
1-1/2 in. X 4 in. Dielectric
Nipple
12 107000424
3/4 X 15 Water Flex Line
13 107000315
Brass Drain Valve
3/4 in. X 2-3/4 in.
14 107000312
Hand Hole Cleanout Cover
15 109000633
Cleanout Bolts 5/16 in. X 3/4
in.
16 107000311
Tank Cleanout Flange Gasket
17 107000314
Anode Rod, Magnesium
18 106000163
Gas Flex Line
19 107000446
3/4 in. X 36 in. Water Flex Line
20 107000383
1 in. X 12 in. Water Flex Line
Replacement Parts for Vertical Models
❶
❶
⓰
⓯
⓮
⓫
⓬
⓭
❸
❽
⓲
❹
❺
❼
❷
⓱
⓴
⓳
❿
❾
(Wire splitter that
connects the
upper and lower
thermistors. Not
shown in image).
Demand Duo H-Series with SENSEI CX Installation Instructions 39
Limited Warranty for Demand Duo H-Series
What Is Covered?
The Rinnai Standard Limited Warranty covers any defects in materials or workmanship when the
product is installed and operated according to Rinnai written installation instructions, subject to the terms
within this Limited Warranty document. This Limited
Warranty applies only to products that are installed
correctly in the United States and Canada. Improper installation may void this Limited Warranty. In order
for this warranty to apply, it is required that you use a trained and qualified professional who has
attended a Rinnai installation training class before installing this water heater. This Limited Warranty
coverage as set out in the table below extends to the original purchaser and subsequent owners, but
only while the product remains at the site of the original installation. This Limited Warranty only extends
to the first / original installation of the product and terminates if the product is moved or reinstalled at a
new location.
*The heat exchanger warranty will be 8 years or 12,000 operation hours, whichever occurs first.
Notes:
• From date of purchase, period of coverage is reduced to 8 years or 12,000 operation hours,
whichever occurs first, if the Rinnai water heater temperature settings exceeds 160°F (71°C).
• The integrated controller has a 1 year warranty on parts.
What Will Rinnai Do?
Rinnai will repair or replace the covered product or any part or component that is defective in materials
or workmanship as set forth in the above table. Rinnai will pay reasonable labor charges associated with
the repair or replacement of any such part or component during the term of the labor warranty period. All
repair parts must be genuine Rinnai parts. All repairs or replacements must be performed by a licensed
professional who is properly trained to do the type of repair.
Replacement of the product may be authorized by Rinnai only at its sole discretion. Rinnai does not
authorize any person or company to assume for it any obligation or liability in connection with the
replacement of the product. If Rinnai determines that repair of a product is not possible, Rinnai may
replace the product with a comparable product at Rinnai’s sole discretion. The warranty claim for
product parts and labor may be denied if a component or product returned to Rinnai is found to be free
of defects in material or workmanship; damaged by improper installation, use or operation; or damaged
during return shipping.
How Do I Get Service?
You must contact a trained and qualified professional for the repair of a product under this Limited
Warranty. For the name of a trained and qualified professional, please contact your place of purchase,
visit the Rinnai website (www.rinnai.us), call Rinnai at 1-800-621-9419 or write to Rinnai at 103
International Drive, Peachtree City, Georgia 30269.
Proof of purchase is required to obtain warranty service. You may show proof of purchase with a dated
sales receipt, or by registering within 30 days of purchasing the product. To register your Rinnai
Tankless Water Heater, please visit www.rinnai.us. For those without internet access, please call
1-866-RINNAI1 (746-6241). Receipt of Registration by Rinnai will constitute proof-of-purchase for this
product. Registration of product installed in new home construction may be verified with a copy of the
closing papers provided by the initial home buyer. However, Registration is not necessary in order to
validate this Limited
Warranty.
Item Warranty Coverage
Heat Exchanger* 8 Years
Storage Tank 6 Years
All Other Parts and Components
5 Years
Reasonable Labor
1 Year
Demand Duo H-Series with SENSEI CX Installation Instructions 40
What Is Not Covered?
This Limited Warranty does not cover any failures or operating difficulties due to the following:
There is no warranty coverage on product installed in a closed loop application, commonly associated
with space heating only applications.
This Limited
Warranty does not apply to any product whose serial number or manufacture date has
been defaced.
This Limited Warranty does not cover any product used in an application that uses chemically treated
water such as a pool or spa heater.
Limitation on Warranties
No one is authorized to make any other warranties on behalf of Rinnai America Corporation. Except as
expressly
provided herein, there are no other warranties, expressed or implied, including, but not limited to
warranties of
merchantability or fitness for a particular purpose, which extend beyond the description of the warranty
herein.
Any implied warranties of merchantability and fitness arising under state law are limited in duration to the
period of coverage provided by this Limited Warranty, unless the period provided by state law is less.
Some states do not allow limitations on how long an implied Limited
Warranty lasts, so the above
limitation may not apply to you.
Rinnai shall not be liable for indirect, incidental, special, consequential or other similar damages that
may arise,
including lost profits, damage to person or property, loss of use, inconvenience, or liability arising from
improper
installation, service or use. Some states do not allow the exclusion or limitation of incidental or
consequential damages, so the above limitation may not apply to you.
This Limited
Warranty gives you specific legal rights, and you may also have other rights which vary
from state to state.
www.rinnai.us/warranty
• Accident, abuse, or misuse
• Alteration of the product or any component part
• Misapplication of this product
• Improper installation (such as but not limited to)
− Product being installed in a corrosive
environment
− Condensate damage
− Improper venting
− Incorrect gas type
− Incorrect gas or water pressure
− Absence of a drain pan under the appliance
• Improper maintenance (such as but not limited
to scale build-up, freeze damage, or vent
blockage)
• Incorrect sizing
• Any other cause not due to defects in materials
or workmanship
• Problems or damage due to fires, flooding,
electrical surges, freezing or any acts of God
• Any damage caused by poor water quality
• Operating the water heater with anything other
than potable water at all times
• Force majeure
